When free agency opens at 4 p.m. Tuesday, the Lions have made it clear they're not going to make a big splash.

Like every team, they have needs, but if they can sign four key free agents of their own -- left tackle Jeff Backus, quarterback Shaun Hill and linebackers Stephen Tulloch and Justin Durant -- they will be in good shape.

A long-term deal with Calvin Johnson would give them much more flexibility. The Pro Bowl wide receiver's cap hit will be $22 million for the final year of his contract. That could be reworked in a new long-term deal.

That's not saying the Lions won't sign any free agents, they just won't be going after the big, sexy names. They could used some depth on the offensive line, at wide receiver and in the defensive backfield. If they don't get Tulloch and Durant signed, they'll be in desperate need of linebackers.

Martin Mayhew, the general manager, has proven he's the patient sort. He's said he knows he might get good players for less money by waiting. He's not afraid to do that because he's still got the draft and he has proven to be adept at making solid trades.

Here's a look at a few defensive back possibilities for the Lions:

-- Cornerback Cortland Finnegan will not be back with the Tennessee Titans. The Lions certainly could use a corner like Finnegan, who played for Jim Schwartz when he was defensive coordinator with the Titans. It all sounds good, but he's likely to be too expensive for the Lions, who will be limited by cap space.

-- Cornerback Brandon Carr was made available when the Kansas City Chiefs signed Stanford Routt. He's considered the second-best free agent cornerback and is expected to earn a big paycheck because there is such a demand for corners. Carr would make a good fit with the Lions and is practically a hometown product. He played high school ball at Flint Carman-Ainsworth and was drafted out of Grand Valley State by the Chiefs. Still, he could be too expensive for the Lions.

-- Tracy Porter, who played for the Saints, would be more affordable for Detroit. He's been inconsistent at times, but he's 26 and could blossom in the right scheme with the right coaching.

-- Safety Dwight Lowery is expected to hit free agency. The Jaguars have tried to re-sign him but they weren't close on the deal. The former cornerback could provide versatility in the defensive backfield. As an added bonus, he's only 25. Still he too could be too pricey for the Lions.

-- Terrell Thomas, age 26, of the Giants is considered a solid No. 2 corner. Sports Illustrated's Peter King lists him as the 49th best free agent available. The USC product didn't play in 2011 due to ACL surgery, so he might be a bit of a gamble. The Giants are trying to re-sign him.

-- Cornerback Carlos Rogers is likely to be available even thought the Niners want him back. Don't see it happening with Detroit. I would expect the Lions to go after younger guys. Rogers is 30, not ancient, but it's up there.

Paula Pasche covers the Lions for The Oakland Press. Follow her on Twitter @PaulaPasche. Read her Lions Lowdown blog at oplions.blogspot.com. Get Lions news delivered directly to your phone by texting the keyword "Lions" to 22700. Msg & Data Rates May Apply. Text HELP for help. Text STOP to cancel.